MIC5268 150mA µCap CMOS LDO Regulator w/Power Good General Description Features The MIC5268 is an efficient, precise CMOS voltage regulator with power good output. The MIC5268 offers better than 3% initial accuracy, and constant ground current (typically 100µA) over load. The MIC5268 also works with low-ESR ceramic capacitors, reducing the amount of board space necessary for power applications, critical in hand-held wireless devices. Key features include current limit, thermal shutdown, a push-pull output for faster transient response, and an active clamp to speed up device turnoff. Available in the IttyBitty™ SOT-23-5 package, the MIC5268 is a fixed 1.2V regulator. Data sheets and support documentation can be found on Micrel’s web site at www.micrel.com. • • • • • • • • • • Power Good indicator Load independent, ultra-low ground current: 100µA 150mA output current Current limiting Thermal shutdown Tight load and line regulation “Zero” off-mode current Stability with low-ESR capacitors Fast transient response TTL-Logic-controlled enable input Applications • Processor power-up sequencing • Laptop, notebook, and palmtop computers • PCMCIA VCC and VPP regulation/switching Ordering Information Part Number Marking Standard Pb-Free Standard Pb-Free Voltage Junction (1) Temp. Range Package MIC5268-1.2BM5 MIC5268-1.2YM5 L512 L512 1.2V –40° to +125°C 5-Pin SOT-23 Note: 1. Other Voltage available. Contact Micrel Marketing for details. Typical Application 47k VIN MIC5268-x.xBM5/YM5 1 5 2 Enable Shutdown VOUT C OUT 3 4 PG EN 1.2V Regulator with Power Good IttyBitty is a trademark of Micrel, Inc. Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com September 2006 1 M9999-91506 Micrel, Inc. MIC5268 Pin Configuration MIC5268-x.x-BM5/YM5 5-Pin SOT-23 (M5) Pin Description Pin Number Pin Name Pin Function 1 IN Supply Input 2 GND 3 EN Enable/Shutdown (Input): CMOS compatible input. Logic high = enable; logic low = shutdown. Do not leave open. 4 PG Power Good Output 5 OUT September 2006 Ground Regulator Output 2 M9999-091506 Micrel, Inc. MIC5268 Absolute Maximum Ratings(1) Operating Ratings(2) Supply Input Voltage (VIN).................................... 0V to +7V Enable Input Voltage (VEN)..................................... 0V to VIN Flag Output Voltage (VPG) ...................................... 0V to VIN Junction Temperature (TJ) ....................................... +150°C Lead Temperature (soldering, 5sec.)......................... 260°C Storage Temperature (Ts) .........................–65°C to +150°C EDS Rating(3) Supply voltage (VIN) ........................................ +2.7V to +6V Enable Input Voltage (VEN)..................................... 0V to VIN Flag Output Voltage (VPG) ...................................... 0V to VIN Junction Temperature (TJ) ........................ –40°C to +125°C Thermal Resistance SOT-23 (θJA)....................................................235°C/W Electrical Characteristics VIN = xx; RL =xx; TA = 25°C, bold values indicate –40°C< TA < +85°C, unless noted. Symbol Parameter Condition VO Output Voltage Accuracy IOUT = 100µA ∆VLNR Line Regulation VIN = 2.7V to 6V ∆VLNR Load Regulation IOUT = 0.1mA to 150mA, Note 4 IQ Quiescent Current VEN ≤ 0.4V (shutdown) PG = NC IGND Ground Pin Current, Note 5 ILIM Min Typ Max Units –3 –4 3 4 % % –0.3 0.3 %/V 3 5 % 0.45 1 µA IOUT = 0mA; VIN = 6.0V 110 150 µA IOUT = 150mA; VIN = 6.0V 110 150 µA Current Limit VOUT = 0V 160 350 mA VIL Enable Input Logic-Low Voltage VIN = 5.5V, regulator shutdown VIH Enable Input Logic-High Voltage VIN = 5.5V, regulator enabled IEN Enable Input Current VIL ≤ 0.4V; VIN = 5.5V 0.01 µA VIH ≥ 1.6V; VIN = 5.5V 0.01 µA Thermal Shutdown Temperature 150 °C Thermal Shutdown Hysteresis 10 °C Enable Input 0.4 V V 1.6 Thermal Protection Power Good, Note 6 VPG Low Threshold High Threshold % of VOUT (PG ON) % of VOUT (PG OFF) VOL PG Output Logic-Low Voltage IL = 10mA 250 IPG Power Good Leakage Current power good off, VPG = 5.5V 0.01 VPG Delay Delay time to Power Good See Timing Diagram 97 % % 500 mV 88 1 µA 5 ms Notes: 1. Exceeding the absolute maximum rating may damage the device. 2. The device is not guaranteed to function outside its operating rating. 3. Devices are ESD sensitive. Handling precautions recommended. 4. Regulation is measured at constant junction temperature using low duty cycle pulse testing. Parts are tested for load regulation in the load range from 0.1mA to 150mA. Changes in output voltage due to heating effects are covered by the thermal regulation specification. 5. Ground pin current is the regulator quiescent current. The total current drawn from the supply is the sum of the load current plus the ground pin current. 6. The power good is a function of the output voltage being 5% low and the detection of one of the following: overcurrent, overtemperature or dropout. See “Applications Information” section for additional information. September 2006 3 M9999-091506 Micrel, Inc. MIC5268 Typical Characteristics September 2006 4 M9999-091506 Micrel, Inc. MIC5268 Block Diagram IN EN Reference Voltage Startup/ Shutdown Control Quickstart PULL UP Thermal Sensor FAULT Error Amplifier Undervoltage Lockout Current Amplifier ACTIVE SHUTDOWN OUT PULL DOWN Out of Regulation Detection PG Overcurrent Dropout Detection Delay GND Timing Diagram September 2006 5 M9999-091506 Micrel, Inc. MIC5268 Enable/Shutdown The MIC5268 comes with an active-high enable pin that allows the regulator to be disabled. Forcing the enable pin low disables the regulator and sends it into a “zero” off-mode-current state. In this state, current consumed by the regulator goes nearly to zero. Forcing the enable pin high enables the output voltage. This part is CMOS and the enable pin cannot be left floating; a floating enable pin may cause an indeterminate state on the output. Transient Response The MIC5268 implements a unique output stage to dramatically improve transient response recovery time. The output is a totem-pole configuration with a Pchannel MOSFET pass device and an N-channel MOSFET clamp. The N-channel clamp is a significantly smaller device that prevents the output voltage from overshooting when a heavy load is removed. This feature helps to speed up the transient response by significantly decreasing transient response recovery time during the transition from heavy load (100mA) to light load (100µA). Input Capacitor An input capacitor is not required for stability. A 1µF input capacitor is recommended when the bulk ac supply capacitance is more than 10 inches away from the device, or when the supply is a battery. Active Shutdown The MIC5268 also features an active shutdown clamp, which is an N-channel MOSFET that turns on when the device is disabled. This allows the output capacitor and load to discharge, de-energizing the load. Application Information Output Capacitor The MIC5268 requires an output capacitor for stability. The design requires 1µF or greater on the output to maintain stability. The capacitor can be a low-ESR ceramic chip capacitor. The MIC5268 has been designed to work specifically with the low-cost, small chip capacitors. Tantalum capacitors can also be used for improved capacitance overtemperature. The value of the capacitor can be increased without bound. X7R dielectric ceramic capacitors are recommended because of their temperature performance. X7R-type capacitors change capacitance by 15% over their operating temperature range and are the most stable type of ceramic capacitors. Z5U and Y5V dielectric capacitors change value by as much 50% and 60% respectively over their operating temperature ranges. To use a ceramic chip capacitor withY5V dielectric, the value must be much higher than an X7Rceramic or a tantalum capacitor to ensure the same minimum capacitance value over the operating temperature range. Tantalum capacitors have a very stable dielectric (10% over their operating temperature range) and can also be used with this device. Power Good The power good output is an open-drain output. It is designed essentially to work as a power-on reset generator once the regulated voltage was up and/or a fault condition. The output of the power good drives low when a fault condition AND an undervoltage detection occurs. The power good output comes back up once the output has reached 97% of its nominal value and a 1ms to 5ms delay has passed. See Timing Diagram. The MIC5268’s internal circuit intelligently monitors overcurrent, overtemperature and dropout conditions and ORs these outputs together indicate some fault condition. This output is fed into an on-board delay circuitry that drives the open drain transistor to indicate a fault. September 2006 Thermal Considerations The MIC5268 is designed to provide 150mA of continuous current in a very small package. Maximum power dissipation can be calculated based on the output current and the voltage drop across the part. To determine the maximum power dissipation of the package, use the junction-to-ambient thermal resistance of the device and the following basic equation: ⎛ TJ(max) − TA PD(max) = ⎜⎜ θ JA ⎝ ⎞ ⎟ ⎟ ⎠ TJ(max) is the maximum junction temperature of the die, 125°C, and TA is the ambient operating temperature. θJA is layout dependent; Table 1 shows examples of junction-to-ambient thermal resistance for the MIC5268. Package θJA Recommended Minimum Footprint θJA 1” Square Copper Clad θJC SOT-23-5 (M5) 235°C/W 185°C/W 145°C/W Table 1. Thermal Resistance The actual power dissipation of the regulator circuit can be determined using the equation: PD = (VIN – VOUT) IOUT + VIN IGND Substituting PD(max) for PD and solving for the operating conditions that are critical to the application will give the maximum operating conditions for the regulator circuit. For example, when operating the MIC5268-1.2BM5 at 50°C with a minimum footprint layout, the maximum input voltage for a set output current can be determined as follows: ⎛ 125°C − 50°C ⎞ PD(max) = ⎜ ⎟ 235°C ⎝ ⎠ PD(max) = 315mW 6 M9999-091506 Micrel, Inc. MIC5268 The junction-to-ambient thermal resistance for the minimum footprint is 235°C/W, from Table 1. The maximum power dissipation must not be exceeded for proper operation. Using the output voltage of 1.2V and an output current of 150mA, the maximum input voltage can be determined. Because this device is CMOS and the ground current is typically 100µA over the load range, the power dissipation contributed by the ground current is < 1% and can be ignored for this calculation. 315mW = (VIN – 1.2V) 150mA 315mW = VIN·150mA – 195mW 510mW = VIN·150mA VIN (max) = 3.4V September 2006 Therefore, a 1.2V application at 150mA of output current can accept a maximum input voltage of 3.4V in a SOT23-5 package. For a full discussion of heat sinking and thermal effects on voltage regulators, refer to the Regulator Thermals section of Micrel’s Designing with Low-Dropout Voltage Regulators handbook. Dual-Supply Operation When used in dual supply systems where the regulator load is returned to a negative supply, the output voltage must be diode clamped to ground. 7 M9999-091506 Micrel, Inc. MIC5268 Package Information 5-Pin SOT-23 (M5) MICREL, INC. 2180 FORTUNE DRIVE SAN JOSE, CA 95131 USA TEL +1 (408) 944-0800 FAX +1 (408) 474-1000 WEB http:/www.micrel.com The information furnished by Micrel in this data sheet is believed to be accurate and reliable. However, no responsibility is assumed by Micrel for its use. Micrel reserves the right to change circuitry and specifications at any time without notification to the customer. Micrel Products are not designed or authorized for use as components in life support appliances, devices or systems where malfunction of a product can reasonably be expected to result in personal injury. Life support devices or systems are devices or systems that (a) are intended for surgical implant into the body or (b) support or sustain life, and whose failure to perform can be reasonably expected to result in a significant injury to the user. A Purchaser’s use or sale of Micrel Products for use in life support appliances, devices or systems is a Purchaser’s own risk and Purchaser agrees to fully indemnify Micrel for any damages resulting from such use or sale. © 2002 Micrel, Incorporated. September 2006 8 M9999-091506